Help with my avocado plant, I've had it for 3 years and I think it's dying

I grew an avocado plant from a costco avocado and it was doing fine, but recently the leaves are dying from the tips and droopy even though i'm keeping the soil moist. Should I repot into a bigger pot or add fertilizer? I live in an apartment so I'm not sure how to increase sunlight. I'm seriously attached to the stupid thing and I don't know what to do